A novel engineered IL-21 receptor arms T-cell receptor-engineered T cells (TCR-T cells) against hepatocellular carcinoma.

Strategies to improve T cell therapy efficacy in solid tumors such as hepatocellular carcinoma (HCC) are urgently needed. The common cytokine receptor γ chain (γc) family cytokines such as IL-2, IL-7, IL-15 and IL-21 play fundamental roles in T cell development, differentiation and effector phases. This study aims to determine the combination effects of IL-21 in T cell therapy against HCC and investigate optimized strategies to utilize the effect of IL-21 signal in T cell therapy. The antitumor function of AFP-specific T cell receptor-engineered T cells (TCR-T) was augmented by exogenous IL-21 in vitro and in vivo. IL-21 enhanced proliferation capacity, promoted memory differentiation, downregulated PD-1 expression and alleviated apoptosis in TCR-T after activation. A novel engineered IL-21 receptor was established, and TCR-T armed with the novel engineered IL-21 receptors (IL-21R-TCR-T) showed upregulated phosphorylated STAT3 expression without exogenous IL-21 ligand. IL-21R-TCR-T showed better proliferation upon activation and superior antitumor function in vitro and in vivo. IL-21R-TCR-T exhibited a less differentiated, exhausted and apoptotic phenotype than conventional TCR-T upon repetitive tumor antigen stimulation. The novel IL-21 receptor in our study programs powerful TCR-T and can avoid side effects induced by IL-21 systemic utilization. The novel IL-21 receptor creates new opportunities for next-generation TCR-T against HCC.

A spatiotemporal atlas of mouse liver homeostasis and regeneration.

The mechanism by which mammalian liver cell responses are coordinated during tissue homeostasis and perturbation is poorly understood, representing a major obstacle in our understanding of many diseases. This knowledge gap is caused by the difficulty involved with studying multiple cell types in different states and locations, particularly when these are transient. We have combined Stereo-seq (spatiotemporal enhanced resolution omics-sequencing) with single-cell transcriptomic profiling of 473,290 cells to generate a high-definition spatiotemporal atlas of mouse liver homeostasis and regeneration at the whole-lobe scale. Our integrative study dissects in detail the molecular gradients controlling liver cell function, systematically defining how gene networks are dynamically modulated through intercellular communication to promote regeneration. Among other important regulators, we identified the transcriptional cofactor TBL1XR1 as a rheostat linking inflammation to Wnt/ß-catenin signaling for facilitating hepatocyte proliferation. Our data and analytical pipelines lay the foundation for future high-definition tissue-scale atlases of organ physiology and malfunction.

Noncanonical regulation of HOIL-1 on cancer stemness and sorafenib resistance identifies pixantrone as a novel therapeutic agent for HCC.

BACKGROUND AND AIMS: Cancer stem cells (CSCs) contribute to therapy resistance in HCC. Linear ubiquitin chain assembly complex (LUBAC) has been reported to accelerate the progression of cancers, yet its role in the sorafenib response of HCC is poorly defined. Herein, we investigated the impact of LUBAC on sorafenib resistance and the CSC properties of HCC, and explored the potential targeted drugs. APPROACH AND RESULTS: We found that HOIL-1, but not the other components of LUBAC, played a contributing role in LUBAC-mediated HCC sorafenib resistance, independent of its ubiquitin ligase activity. Both in vitro and in vivo assays revealed that the upregulated HOIL-1 expression enhanced the CSC properties of HCC. Mechanistically, HOIL-1 promoted sorafenib resistance and the CSC properties of HCC through Notch1 signaling. Mass spectrometry, co-immunoprecipitation, western blot, and immunofluorescence were used to determine that the A64/Q65 residues of HOIL-1 bound with the K78 residue of Numb, resulting in impaired Numb-mediated Notch1 lysosomal degradation. Notably, pixantrone was screened out by Autodock Vina, which was validated to disrupt HOIL-1/Numb interaction to inhibit Notch1 signaling and CSC properties by targeting the Q65 residue of HOIL-1. Moreover, pixantrone exerted synergistic effects with sorafenib for the treatment of HCC in different HCC mouse models. CONCLUSIONS: HOIL-1 is critical in promoting sorafenib resistance and CSC properties of HCC through Notch1 signaling. Pixantrone targeting HOIL-1 restrains the sorafenib resistance and provides a potential therapeutic intervention for HCC.

IL-21 collaborates with anti-TIGIT to restore NK cell function in chronic HBV infection.

Available therapies for chronic hepatitis B virus (HBV) infection are not satisfying, and interleukin-21 (IL-21) and checkpoint inhibitors are potential therapeutic options. However, the mechanism underlying IL-21 and checkpoint inhibitors in treating chronic HBV infection is unclear. To explore whether IL-21 and checkpoint inhibitors promote HBV clearance by modulating the function of natural killer (NK) cells, we measured the phenotypes and functions of NK cells in chronic HBV-infected patients and healthy controls on mRNA and protein levels. We found that chronic HBV infection disturbed the transcriptome of NK cells, including decreased expression of KLRK1, TIGIT, GZMA, PRF1, and increased expression of CD69. We also observed altered phenotypes and functions of NK cells in chronic HBV-infected patients, characterized by decreased NKG2D expression, increased TIGIT expression and impaired interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) production. Furthermore, these alterations cannot be restored by telbivudine treatment but can be partially restored by IL-21 and anti-TIGIT stimulation. IL-21 upregulated the expression of activating receptor CD16, CD69, and NKG2D on NK cells, enhanced IFN-γ production, cytolysis, and proliferation of NK cells, while anti-TIGIT promoted IFN-γ production in CD56dim subset exclusively in chronic HBV infected patients. Additionally, IL-21 was indispensable for anti-TIGIT in HBsAg clearance in mice bearing HBV. It enhanced IFN-γ production in splenic NK cells rather than intrahepatic NK cells, indicating a brand-new mechanism of IL-21 in HBV clearance when combined with anti-TIGIT. Overall, our findings contribute to the design of immunotherapy through enhancing the antiviral efficacy of NK cells in chronic HBV infection.

Alcohol reshapes a liver premetastatic niche for cancer by extra- and intrahepatic crosstalk-mediated immune evasion.

Cancer metastatic organotropism is still a mystery. The liver is known to be susceptible to cancer metastasis and alcoholic injury. However, it is unclear whether and how alcohol facilitates liver metastasis and how to intervene. Here, we show that alcohol preferentially promotes liver metastasis in colon-cancer-bearing mice and post-surgery pancreatic cancer patients. The mechanism is that alcohol triggers an extra- and intrahepatic crosstalk to reshape an immunosuppressive liver microenvironment. In detail, alcohol upregulates extrahepatic IL-6 and hepatocellular IL-6 receptor expression, resulting in hepatocyte STAT3 signaling activation and downstream lipocalin-2 (Lcn2) upregulation. Furthermore, LCN2 promotes T cell-exhaustion neutrophil recruitment and cancer cell epithelial plasticity. In contrast, knocking out hepatocellular Stat3 or systemic Il6 in alcohol-treated mice preserves the liver microenvironment and suppresses liver metastasis. This mechanism is reflected in hepatocellular carcinoma patients, in that alcohol-associated signaling elevation in noncancerous liver tissue indicates adverse prognosis. Accordingly, we discover a novel application for BBI608, a small molecular STAT3 inhibitor that can prevent liver metastasis. BBI608 pretreatment protects the liver and suppresses alcohol-triggered premetastatic niche formation. In conclusion, under extra- and intrahepatic crosstalk, the alcoholic injured liver forms a favorable niche for cancer cell metastasis, while BBI608 is a promising anti-metastatic agent targeting such microenvironments.

Causal associations between chronic hepatitis B and COVID-19 in East Asian populations.

BACKGROUND: The relationship between chronic hepatitis B (CHB) and Coronavirus disease 2019 (COVID-19) has been inconsistent in traditional observational studies. METHODS: We explored the total causal and direct causal associations between CHB and the three COVID-19 outcomes using univariate and multivariate Mendelian randomization (MR) analyses, respectively. Genome-wide association study datasets for CHB and COVID-19 were obtained from the Japan Biobank and the COVID-19 Host Genetics Initiative, respectively. RESULTS: Univariate MR analysis showed that CHB increased the risk of SARS-CoV-2 infection (OR = 1.04, 95% CI 1.01-1.07, P = 3.39E-03), hospitalized COVID-19 (OR = 1.10, 95% CI 1.06-1.13, P = 7.31E-08), and severe COVID-19 (OR = 1.16, 95%CI 1.08-1.26, P = 1.43E-04). A series of subsequent sensitivity analyses ensured the stability and reliability of these results. In multivariable MR analyses adjusting for type 2 diabetes, body mass index, basophil count, and smoking, genetically related CHB is still positively associated with increased risk of SARS-CoV-2 infection (OR = 1.06, 95% CI 1.02-1.11, P = 1.44E-03) and hospitalized COVID-19 (OR = 1.12, 95% CI 1.07-1.16, P = 5.13E-07). However, the causal link between CHB and severe COVID-19 was attenuated after adjustment for the above variables. In addition, the MR analysis did not support the causal effect of COVID-19 on CHB. CONCLUSIONS: This study provides evidence that CHB increases COVID-19 susceptibility and severity among individuals of East Asian ancestry.

Effect of prophylactic antiviral intervention on T cell immunity in hepatitis B virus-infected pregnant women.

BACKGROUND: Antiviral intervention in hepatitis B virus (HBV)-infected pregnant women can effectively reduce mother-to-child transmission. However, the immunological characteristics of pregnant women with chronic HBV infection and the effects of antiviral intervention during pregnancy on maternal immune response remain unknown. We aimed to investigate these effects by comparing mothers who received antiviral intervention during pregnancy with those who did not. METHODS: Pregnant women positive for hepatitis B surface antigen and hepatitis B e-antigen (HBsAg+ HBeAg+) were enrolled at delivery, including 34 received prophylactic antiviral intervention during pregnancy (AVI mothers) and 15 did not (NAVI mothers). T lymphocyte phenotypes and functions were analysed using flow cytometry. RESULTS: At delivery, maternal regulatory T cell (Treg) frequency in AVI mothers was significantly higher than that in NAVI mothers (P < 0.002), and CD4+ T cells in AVI mothers displayed a decreased ability to secrete IFN-γ (P = 0.005) and IL-21 (P = 0.043), but an increased ability to secrete IL-10 and IL-4 (P = 0.040 and P = 0.036), which represented a higher Treg frequency, enhanced Th2 response and suppressed Th1 response. Treg frequency among AVI mothers was correlated negatively with serum HBsAg and HBeAg levels. After delivery, the ability of CD4+ T cells or CD8+ T cells to secrete IFN-γ or IL-10 was similar and no significant difference in Treg frequency was found between the two groups. CONCLUSIONS: Prophylactic antiviral intervention during pregnancy has an effect on T cell immunity in pregnant women, which was characterised by increased maternal Treg frequency, enhanced Th2 response and suppressed Th1 response at delivery.

Peyer's patch-involved gut microbiota facilitates anti-HBV immunity in mice.

BACKGROUND: Gut microbiota is crucial for immune homeostasis and is associated with the prognosis of chronic hepatitis B infection. Peyer's patches (PPs), characterized by intestinal mucosa localization, are involved in the gut microbiota-mediated immune response. However, whether and how PPs orchestrate gut microbiota-modulated anti-hepatitis B virus (HBV) response remain elusive. This study aims to elucidate the role of PPs in gut microbiota-mediated anti-HBV adaptive immunity. METHODS: We investigated the effects of gut microbiota and PPs on adaptive immune responses by transcriptomic, phenotypic, and functional analyzes from an HBV mouse model with gut commensal microbiota and PP-depleting interventions. RESULTS: Depletion of gut microbiota impaired systemic adaptive immune responses, resulting in a delayed HBV antigen clearance. Differentially expressed genes analysis of PPs revealed that pathways related to adaptive immune responses were significantly downregulated in gut microbiota-deficient mice. Notably, the depletion of PPs could abolish gut microbiota-boosted intrahepatic HBV-specific T cell response, leading to a higher serum hepatitis B surface antigen level in mice. CONCLUSION: PPs orchestrate gut microbiota-mediated intrahepatic anti-HBV cellular immunity, underlining the significance of remote manipulating the "gut microbiota-PPs" axis for achieving optimum anti-HBV response.

Cell atlas of CCl 4-induced progressive liver fibrosis reveals stage-specific responses.

Chronic liver injury leads to progressive liver fibrosis and ultimately cirrhosis, a major cause of morbidity and mortality worldwide. However, there are currently no effective anti-fibrotic therapies available, especially for late-stage patients, which is partly attributed to the major knowledge gap regarding liver cell heterogeneity and cell-specific responses in different fibrosis stages. To reveal the multicellular networks regulating mammalian liver fibrosis from mild to severe phenotypes, we generated a single-nucleus transcriptomic atlas encompassing 49 919 nuclei corresponding to all main liver cell types at different stages of murine carbon tetrachloride (CCl 4)-induced progressive liver fibrosis. Integrative analysis distinguished the sequential responses to injury of hepatocytes, hepatic stellate cells and endothelial cells. Moreover, we reconstructed cell-cell interactions and gene regulatory networks implicated in these processes. These integrative analyses uncovered previously overlooked aspects of hepatocyte proliferation exhaustion and disrupted pericentral metabolic functions, dysfunction for clearance by apoptosis of activated hepatic stellate cells, accumulation of pro-fibrotic signals, and the switch from an anti-angiogenic to a pro-angiogenic program during CCl 4-induced progressive liver fibrosis. Our dataset thus constitutes a useful resource for understanding the molecular basis of progressive liver fibrosis using a relevant animal model.

Differential response of HBV envelope-specific CD4 + T cells is related to HBsAg loss after stopping nucleos(t)ide analogue therapy.

BACKGROUND AND AIM: Long-term maintenance of viral control, even HBsAg loss, remains a challenge for chronic hepatitis B (CHB) patients undergoing nucleos(t)ide analogue (NA) discontinuation. This study aimed to investigate the relationship between HBV-specific T-cell responses targeting peptides spanning the whole proteome and clinical outcomes in CHB patients after NA discontinuation. APPROACH AND RESULTS: Eighty-eight CHB patients undergoing NA discontinuation were classified as responders (remained relapse-free up to 96 weeks) or relapsers (relapsed patients who underwent NA retreatment for up to 48 weeks and reachieved stable viral control). HBV-specific T-cell responses were detected at baseline and longitudinally throughout the follow-up. We found responders had a greater magnitude of HBV polymerase (Pol)-specific T-cell responses than relapsers at baseline. After long-term NA discontinuation, simultaneously enhanced HBV Core-induced and Pol-induced responses were observed in responders. Particularly, responders with HBsAg loss possessed enhanced HBV Envelope (Env)-induced responses after short-term and long-term follow-up. Notably, CD4 + T cells accounted for the predominance of HBV-specific T-cell responses. Correspondingly, CD4-deficient mice showed attenuated HBV-specific CD8 + T-cell responses, reduced HBsAb-producing B cells, and delayed HBsAg loss; in contrast, in vitro addition of CD4 + T cells promoted HBsAb production by B cells. Besides, IL-9, rather than PD-1 blockade, enhanced HBV Pol-specific CD4 + T-cell responses. CONCLUSION: HBV-specific CD4 + T-cell responses induced by the targeted peptide possess specificities for long-term viral control and HBsAg loss in CHB patients undergoing NA discontinuation, indicating that CD4 + T cells specific to distinct HBV antigens may endow with divergent antiviral potential.

HBV Core-specific CD4+ T cells correlate with sustained viral control upon off-treatment in HBeAg-positive chronic hepatitis B patients.

BACKGROUND & AIMS: Treatment with nucleos(t)ide analogue (NA) efficiently suppresses viral replication in patients with chronic HBV infection, yet HBV relapses frequently upon NA withdrawal; the detailed immunomodulatory compounds for sustained viral control of HBV upon NA interruption have yet to be fully clarified. This study aimed to elucidate the role of T cells specific for distinct HBV peptides in sustained response upon discontinuation of antiviral treatment. METHODS: A total of 48 patients with HBeAg-positive chronic hepatitis B receiving NA treatment and withdrawal were included longitudinally in a retrospective and prospective cohort. Enzyme-linked immunosorbent spot (ELISpot) and intracellular cytokine staining (ICS) assays were performed to detect IFN-γ producing HBV-specific T cells following stimulation with overlapping peptides covering the whole HBV genome after 10 days of in vitro expansion. RESULTS: ICS assays revealed that T cells specific for HBV Core and Polymerase induced more robust IFN-γ responses compared to Envelope and HBx. Notably, at the time of NA discontinuation, the intensity and breadth of HBV Core peptides-induced responses, predominately targeted by CD4+ T cells but not CD8+ T cells, were associated with sustained viral control upon off-treatment. Further exploration of longitudinal features in patients with sustained viral control revealed that the breadth of HBV-specific T cell responses does not increase following treatment cessation. CONCLUSION: This report emphasizes the essential role of HBV Core-specific CD4+ T cells in sustained response after therapy withdrawal, indicating it is a potential candidate for immunotherapeutic approaches in chronic HBV patients.

Pre-existing immunity to SARS-CoV-2 associates with strong T cell responses induced by inactivated COVID-19 vaccines.

Individuals with a recent common cold coronavirus infection, which leads to pre-existing immunity against SARS-CoV-2, displayed a less severe course of COVID-19. However, the relationship between pre-existing immunity against SARS-CoV-2 and the inactivated-vaccine-induced immune response is still unknown. Here, 31 healthcare workers who received standard two doses of inactivated COVID-19 vaccines (Weeks 0 and 4, respectively) were enrolled, vaccine-induced neutralization and T cell responses were detected, and the correlation between the pre-existing SARS-CoV-2-specific immunity was analyzed. We found the SARS-CoV-2-specific antibodies, pseudovirus neutralization test (pVNT) titers, and spike-specific interferon gamma (IFN-γ) production in CD4+ and CD8+ T cells were significantly elevated after two doses of inactivated vaccines. Interestingly, the pVNT titers after the second dose of vaccination displayed no significant correlation with the pre-existing SARS-CoV-2-specific antibodies or B cells, nor the pre-existing spike-specific CD4+ T cells. Notably, the spike-specific T cell response after the second dose of vaccination was positively correlated with the pre-existing receptor binding domain (RBD)-specific B cells and CD4+ T cells, which were documented by the frequencies of RBD-binding B cells, the breadth of RBD-specific B cell epitopes, and the frequency of IFN-γ-expressing RBD-specific CD4+ T cells. Overall, the inactivated-vaccine-induced T cell responses, not the inactivated-vaccine-induced neutralization, closely correlated with pre-existing immunity to SARS-CoV-2. Our results provide a better understanding of inactivated-vaccine-induced immunity and help predict the immunogenicity induced by inactivated vaccines in individuals.

CTLA4+CD4+CXCR5-FOXP3+ T cells associate with unfavorable outcome in patients with chronic HBV infection.

BACKGROUND: A major barrier to achieving a favorable outcome of chronic HBV infection is a dysregulated HBV-specific immune response resulting from immunosuppressive features of FOXP3+ T cells. A better definition of FOXP3+ T cells is essential for improving the prognosis of HBV infection. We aimed to investigate the role of CD4+CXCR5-FOXP3+ T cells with CTLA4 expression in patients with chronic HBV infection. METHODS: Treatment-naïve chronic HBV-infected patients, HBV-related hepatic failure, and a longitudinal cohort of chronic hepatitis B (CHB) patients with nucleos(t)ide analogue treatment were enrolled for analysis of CD4+CXCR5-FOXP3+ T cell responses by flow cytometry and single-cell RNA sequencing (scRNA-seq). RESULTS: ScRNA-seq revealed that circulating CD4+CXCR5-FOXP3+ T cells presented distinct inhibitory features compared to spleen tissue. Meanwhile, patients with treatment-naïve chronic HBV infection or with HBV-related hepatic failure showed an upregulation of immune-suppressive features (PD-1, CTLA4, GITR) on CD4+CXCR5-FOXP3+T cells; in vitro analysis found HBeAg and HBcAg stimulation induced elevated levels of inhibitory molecules. Notably, the frequency of CTLA4+CD4+CXCR5-FOXP3+ T cells was positively correlated with HBV DNA levels, and longitudinal analysis demonstrated a high frequency of this subset at 12 weeks of antiviral treatment predicted unfavorable outcome in CHB patients. CONCLUSIONS: CTLA4+CD4+CXCR5-FOXP3+ T cells are related to unfavorable outcomes in HBV-infected patients; these data indicated that alleviating CTLA4+CD4+CXCR5-FOXP3+ T cells may improve the prognosis of HBV infection.

Interferon α facilitates anti-HBV cellular immune response in a B cell-dependent manner.

OBJECTIVES: Dissecting the underlying mechanism of T cells remodeling mediated by interferon α (IFN-α) is indispensable for achieving an optimum therapeutic response in chronic hepatitis B (CHB) patients. However, little is known about B cells in this process. This study aims to elucidate the roles of B cells in IFN-α-mediated anti-hepatitis B virus (HBV) cellular immunity. METHOD: The effects of B cells on IFN-α-mediated T cell response were investigated in B cell-deficient mouse model with HBV and IFN-α plasmid hydrodynamic injection. Single-cell RNA sequencing was performed to dissect the crosstalk among B cell and T cell subsets and the underlying molecule and pathway signatures on longitudinal blood samples from IFN-α-treated CHB patients. RESULTS: B cell depletion impaired the functional T cell subsets, including HBV-specific CD8+ T cells, and engendered a delayed HBV clearance. IFN-α treatment boosted the response of HBV-specific CD8+ T cells, whereas such effects disappeared in B cell-deficient mice. The underlying mechanisms were associated with IFN-α-reinforced connections of B cells toward T cells as mediated by the antigen presentation and costimulatory functions in B cells. CONCLUSION: IFN-α orchestrates protective HBV-specific cellular immunity in a B cell-dependent manner.

Impaired CD8+ T cells in term pregnancy decidua with chronic hepatitis B virus infection.

PROBLEM: Hepatitis B virus (HBV) infection is more likely to develop a state of chronicity in early life, particularly mother-to-child transmission (MTCT) of HBV in the fetus during pregnancy. Till now, little is known about the impact of chronic HBV infection on the immune status of the maternal-fetus interface, and the immune profile of placental lymphocytes in MTCT of HBV is poorly understood. METHOD OF STUDY: Thirteen term pregnant women with chronic HBV infection (HBV-PW) and thirteen normal pregnant women as healthy control (HC-PW) were enrolled. The profile of placental immune cells and paired peripheral blood were analyzed by flow cytometry and immunohistochemistry. RESULTS: Compared with HC-PW, the frequency of CD8+ T cells from the term placenta of HBV-PW was significantly reduced. These cells showed decreased expression of activation molecules CD69 and HLA-DR; thus, decidual CD8+ T cells from HBV-PW demonstrated hypofunctional signature as evidenced by significantly reduced production of IFN-γ, as well as compromised ability of degranulation and proliferation. CONCLUSIONS: These findings supported that hypoactivated decidual CD8+ T cells might possess compromised ability in chronically HBV-infected term pregnant women. Our study provides robust evidence for the necessity and importance of antiviral intervention in HBV-PW to prevent MTCT of HBV.

Longitudinal mapping of hepatitis B vaccine-induced B-cell linear epitopes in healthy individuals.

The elimination of hepatitis B virus (HBV) infection is partially facilitated by the prophylactic HB vaccine. As the loss of seroprotection over time remains a conundrum for long-lasting protection, a comprehensive dynamic analysis of immunogenic targets of the HB vaccine will provide novel insights into the improvement and design of potential targets. In this study, 36 healthy subjects without prior history of hepatitis B infection and negative for hepatitis B surface antibody (anti-HBs) were enrolled. Participants were given a series of three doses of HB vaccine on a 0-, 1-, and 6-month schedule and longitudinally followed up. We systematically mapped 55 overlapping 15-mer peptides covering the small S protein of hepatitis B virus (SHBs) of vaccinees' serum samples at seven time points by performing an ELISA assay. Additionally, the frequencies and function dynamics of adaptive immune response were assessed by flow cytometry. We found that the SHBs peptide coverage presented an overall upward trend along with the vaccination progress, and the individual subpartition recognition was strongly correlated with the anti-HBs titers. Moreover, we identified one dominant epitope (S29) located on "a determinant region" associated with effective vaccine response. Besides, significant correlations between the proportion of plasmablasts and proliferating B cells and levels of anti-HBs were ascertained. Taken together, our data characterized the dynamics of HB vaccine-induced neutralizing antibodies against B-cell linear epitopes on SHBs and adaptive immune response, which will be constructive to develop the next-generation vaccine.

Vaccination of cats with Sad23L-nCoV-S vaccine candidate against major variants of SARS-CoV-2.

Cats are susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and risk transmitting viruses to naive cats or humans. Here, based on our novel adenovirus-vectored COVID-19 vaccine, the immunogenicity of Sad23L-nCoV-S vaccine was evaluated in cats by prime-boost vaccinations. Five cats were primed with a dose of 108 plaque-forming units (PFUs) Sad23L-nCoV-S vaccine and then boosted with an equal dose of same vaccine at a 4-week interval. Cat serum neutralizing antibody (NAb) titers (the sample dilution at which 50% inhibitory concentration [IC50]) were measured as IC50 15,849 to wild-type strain, IC50 6,591 to Alpha, IC50 2,315 to Beta, IC50 2,744 to Gamma, IC50 1,848 to Delta, and IC50 318 to Omicron variants of pseudotyped SARS-CoV-2 viruses at week 6 post-prime vaccination. All NAb levels to these five variants were ≥IC50 49 from vaccinated cats at week 10, while 48.8% to Delta and 100% to Omicron variants were

Hepatocyte-Derived L-Carnitine Restricts Hepatitis B Surface Antigen Loss Through an Immunosuppressive Effect on Germinal Center-Related Immune Cells.

BACKGROUND: The outcome of hepatitis B virus (HBV) infection is significantly affected by host immune response; herein, we aim to dissect the effect of L-carnitine (L-Cn) on germinal center (GC)-related immune cells and the influence on the prognosis of HBV infection. METHODS: In vitro and in vivo experiments were performed in patients with chronic HBV infection and a hydrodynamic injection mouse model. RESULTS: In vitro assays revealed that L-Cn significantly reduced GC-related immune responses and enhanced immunosuppressive profiles. Intriguingly, L-Cn released from lysed hepatocytes was associated with the degree of liver damage. Besides, the administration of L-Cn in an HBV mouse model resulted in delayed clearance of hepatitis B surface antigen (HBsAg) in serum and decreased GC formation in the spleen. Notably, patients with HBsAg loss showed decreased plasma L-Cn levels, and longitudinal observations found that low baseline levels of L-Cn were associated with a favorable treatment response in patients with chronic hepatitis B. CONCLUSIONS: The suppressive effect of hepatocyte-derived L-Cn on GC-related immune cells may contribute to the inability of HBsAg clearance in chronic HBV infection, indicating that L-Cn might serve as a potential therapeutic target for the treatment of HBV infection.

Cytokines and Chemokines in HBV Infection.

Chronic hepatitis B virus (HBV) infection remains a leading cause of hepatic inflammation and damage. The pathogenesis of chronic hepatitis B (CHB) infection is predominantly mediated by persistent intrahepatic immunopathology. With the characterization of unique anatomical and immunological structure, the liver is also deemed an immunological organ, which gives rise to massive cytokines and chemokines under pathogenesis conditions, having significant implications for the progression of HBV infection. The intrahepatic innate immune system is responsible for the formidable source of cytokines and chemokines, with the latter also derived from hepatic parenchymal cells. In addition, systemic cytokines and chemokines are disturbed along with the disease course. Since HBV is a stealth virus, persistent exposure to HBV-related antigens confers to immune exhaustion, whereby regulatory cells are recruited by intrahepatic chemokines and cytokines, including interleukin-10 and transforming growth factor ß, are involved in such series of causal events. Although the considerable value of two types of available approved treatment, interferons and nucleos(t)ide analogues, effectively suppress HBV replication, neither of them is sufficient for optimal restoration of the immunological attrition state to win the battle of the functional or virological cure of CHB infection. Notably, cytokines and chemokines play a crucial role in regulating the immune response. They exert effects by directly acting on HBV or indirectly manipulating target immune cells. As such, specific cytokines and chemokines, with a potential possibility to serve as novel immunological interventions, combined with those that target the virus itself, seem to be promising prospects in curative CHB infection. Here, we systematically review the recent literature that elucidates cytokine and chemokine-mediated pathogenesis and immune exhaustion of HBV infection and their dynamics triggered by current mainstream anti-HBV therapy. The predictive value of disease progression or control and the immunotherapies target of specific major cytokines and chemokines in CHB infection will also be delineated.